An electroluminescent (EL) display, such as an active matrix organic light emitting diode (AMOLED) display, may include an array of pixels. In addition, each of the pixels may include an EL device, a switching transistor for transfer data that contains information on luminescence, and a driving transistor for driving the EL device to emit light according to the data. While such EL display enjoys the benefit of relatively low power consumption, display non-uniformity may exist among pixels due to process factors in semiconductor manufacturing. It may thus be desirable to have a circuit that solves the problem.